Electric circuit interrupter



Nov. 14,1939. w. no 2,180,147

ELECRIC CIRCUIT INTERRUPTER Filed' June 3, 1337 lnye'ntdrz. V wilhejmHp'p, by W 6.0?

is Attorney.

I Patented Nov. 14, 1939 UNITED STATES PATENT OFFICE) 2 ,180,147 amcrmocmcmr m'rmmur'rea Wilhelm.- Hiipp,

Berlin-Heiligensee, Germany, as-

signor to General Electric Company, a corporation of New YorkApplication June 3,

In Germany 1937, Serial No. 146,183

July 21, 1936 v 1% Claims. (Cl. 200 -14-1 proved circuit interrupter ofthe aforesaid type determined position.

, and forming a part of which is effective to interrupt the are withoutinvolving high induced voltages, fiashover or reignition of the arc andexcessive deterioration of the interrupter structure.

Magnetic blowout circuit interrupters, such as air circuit breakers forexample, have been proposed wherein a strong blowout field is utilizedto extend and lengthen the are rapidly into an arc cooling structure,such as are splitters for example. In certain instances the magneticblowout field may be so powerful that the arc, referring specifically toan inductive alternating current circuit, is extended to such length andruptured so suddenly that high flashover voltages are induced causingdamage to the installations and under certain circumstances fiashover orreignition of the arc.

In the case of alternating current it is particularly important that theblowout field be controlled, since a comparatively powerful blowout andleakage field may extend the arc to such. length before rupture that thelarge quantities of ionized gases formed by the arc tend to causereignition after interruption at the current zero.

In accordance with the present invention a comparatively powerfulblowout field acts locally on the are so as to cause high accelerationof the extending movement thereof, and the field is weakened or opposedafter predetermined extension of the arc so as to maintain the are or atleast a portion thereof at a substantiafly pre- Interruption of the arctakes place at the preferred extended length thereof so that dangerousflashoveryoltages and reignition of the are are substantially precluded.

My invention will be more fully 'set forth in the following descriptionreferring to the accompanying'drawing, and the featurespf novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to this specification.

Referring to the drawing,

Fig. 1 is an elevational view, partly in section, of a magnetic blow-outcircuit breaker embodying the present invention; Fig. 2 is a plan view,partly in section, of the electrode or contact structure of Fig. 1, andFig. 3 is a diagrammatic illustration of the action of the blow-outfield on the arc.

The circuit interrupter illustrated comprises relatively movablecontacts or electrodes l and there is provided electromagnetic 2 betweenwhich an arc is formed upon opening of the circuit. Each contact iselectrically connected to an arcing horn 3. For the purpose ofconcentrating a magentic blow-out field at a. localized region betweenthe contacts, magnetic core material, such as iron, is inserted at 4 ineaclr contact so as to restrict the contact crosssection at 5. The cores4 are provided with iron pole pieces 6 which are also set in recesses"in the opposite sides of the contacts as illustrated by When thecontacts are separated to open the circuit, an arc is formed in thespace between the contacts. The blow-out in a well-known manner by theelectromagnetic means above described, extends from the pole pieces intothe arc gap, as indicated. by the flux lines I (Fig. 2), and rapidlymoves the arc to the top of the contacts at 8 as illustrated by Fig. 1.This part of the movement of the arc is very rapid as a comparativelystrong magnetic field is concentrated onthe arc during its initialextension. As the arc continues to extend under influence of the field,it travels over the contact surfaces to the arcing horns 3 as indicated.

For the purpose of limiting extension of the are beyond a predeterminedlength orposition, means at 9 for creating an opposing field. In thepresent instance, this means comprises a core"! of magnetic material,such as iron, and a. conducting ring H composed of copper for exampleforming a short-circuited conductor about the core. The core, 10 is ofappreciable mass as illustrated so that it occupies an appreciable partof the arc chamber and is located in the usual arc chute I2transversely-of the direction of extension of theme and intermediate theends thereof. The spacing of the core from the initial arc position at 8depends on the interrupting requirements of the breaker and, in certaincases, may be comparatively close thereto.

As above pointed out, separation of the contacts l and 2 to open thecircuit causes formation of an arc therebetween which is driven rapidlyby the concentrated field to the upper position at 8 and from there bythe leakage field toward the core structure l0 as indicated by thedirection arrows. The movement of the arc roots along the upper surfacesof the contacts is slower by reason of the reduction in strengtl'P ofthe blow-out field, and the arc is extended to the position indicated atl3 wherein the core limits further appreciable extension of the centralpart of the arc.

field, which is created duces in the core. Immediately it has passed theneutral zone N-N to position is, however, the

reversed blow-out field tends to drive it down= word as indicated by thedirection arrows. The central part of the are, therefore, tends toadjust itself to an intermediate position with respect to the core, sothat it is not further ezr= tended by the blow-out field. The endportions and extremities of the are are, however, still subject to theweakened blow-out field and are extended a limited distance toward thearc split= ters id as indicated where the arc is interrupted at acurrent zero. The are in this position, i. e. I18, can oscillate due tothe pulsations or the A. C. blow-out field and at each oscillation willbe driven into the arc splitters, if not interrupted at the firstcurrent zero.

For the purpose oi maintaining the arc in the central plane of thecontacts and centrally oi the arc chute, the arc surfaces i and 2' oithe contacts are symmetrical with respect to the magnetic blow-out held.That is, the siufaces can be mutually convex so as to conform generallyto the flux paths at each contact. Accordingly, the are, if originatingatone side 01? the contacts, is acted on by a iorce component tending todrive it toward the central axes indicated at dhe are, therefore, is wein a concentrated blotv=' out held when initially formed.

it should be understood that my invention m not limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the arttrlthout departing from the spirit of my invention. .7

What I claim as new and desire to secure by Letters Patent or the UnitedStates is:

1. An electric circuit internniter oi thenoag= assure? netic blowouttype comprising electrodes between which an arc is formed upon openingof the circuit, an arc-extinguishing chamber, magnetic blowout means forextending said arc into said chamber, and electromagnetic meanspositioned in said chamber substantially transversely of the are pathfor creating an opposing field in accordance with the currentoi said areand thereby preventing extension of said are beyond the limits definedby said opposing field, said electromagnetic means comprising an ii'oncore of appreciable size as compared with the size of said chamber and ashort-circuited conductor sur rounding said core.

2. An electric circuit breaker comprising relatively movable contactsbetween which an arc may form upon opening or the circuih'means forcreating" a magnetic field for rapidly extendins said arc beyond saidcontacts, an are extinguishing chamber into which said are is extended,and means located in said chamber transversely of the path of extensionoi said are for creating an opposing nelcl tending to limit extension ofsaid are beyond a predetermined position, said means comprising ametallic core oi magnetic material occupying an appreciable part of saidchamber and extending between side walls thereof, and a short circuitingconductor surrounding said core.

3. An electric circuit breaker comprising rela= tively movable contactsbetween which an arc may form upon opening or the circuit, means forcreating a magnetic field for rapidly extending said are beyond saidcontacts, an arc extinguishthe chamber into which said are is extended,and means located in said chamber transversely of the path of extensionor said are for creating an opposing iield tending to limit extension oisaid are beyond a predetermined position, said means comprising an ironcylinder exmnding between side Walls of said chamber, and a shortcircuiting copper sleeve surrounding said cylinder.

none.

